Composite structures are typically constructed from multiple layers or plies. These plies may include a variety of materials such as carbon fiber, various other fibers, metal foils, and the like. In addition, the plies may be pre-impregnated with a resin and are often dispensed from a roll or spool. In roll form, the ply material is referred to as “tape” and typically includes a paper backing film. This backing film generally prevents pre-impregnated ply material (prepreg) from adhering to itself and aids in handling the ply as the ply is applied to the tool and the layup. In particular, at the beginning and end of each ply placement, the ply material is generally cut to match the profile of the layup while the backing film is left intact. In this manner, the intact backing film is utilized to guide the severed ply on to the layup. During the layup process, the backing film is removed prior to placement of any subsequent ply. To provide support for the material being cut and facilitate cutting to a proper depth, an anvil is typically utilized. The anvil is situated on the opposite side of the tape from the cutting tool and lays along the cutting path or is controlled to move in unison with the cutting tool.
A disadvantage associated with conventional anvils is the relatively high precision required to install and prepare them for use. Minor deviations in height adjustment may result in incomplete cuts of the ply material or cutting of the backing film. In particular, cuts in the backing film, introduced during the ply cutting procedure, often serve as a starting point for a tear. As the backing film is removed, torn backing film may remain on the ply, may fowl the ply placement head, and/or may lead to breakage of the backing film.
Another disadvantage associated with conventional anvils is that essentially any contact between the cutting tool and the anvil while setting up the cutting assembly or during use may result in damage to the cutting tool and/or the anvil. Even apparently minor damage to the cutting tool may produce unsatisfactory cutting performance and thus, require cutting tool replacement or regrinding. Damage to the anvil typically manifests itself as score marks. These score marks may cause cutting problems resulting from an altered cutting surface and generally tend to increase the drag of the tape as the tape is fed through the tape laying head. Down time associated with replacement of the cutting tool and/or anvil wastes resources.
Accordingly, it is desirable to provide a anvil that is capable of overcoming the disadvantages described herein at least to some extent.